In my U.S. Pat. No. 4,272,087, I describe a drill chuck having a chuck body connected to a drill spindle connectible to the drive of a hammer or percussion drill capable of rotating the chuck while imparting axial blows to the chuck and a tool (i.e. a drill bit) held therein.
The chuck body accommodates a holding fixture for clamping one drill bit between jaws which are movable via a tightening ring connected to an adjusting sleeve.
The sleeve is provided with a toothed skirt which is engageable by a locking member so that no unintentional rotational movement of the sleeve relative to the chuck body in loosening direction is possible and thus an undesired unlocking of the chuck is prevented. In order to allow a loosening of the drill bit, the sleeve cooperates with a loosening ring which acts on the locking member to disengage the latter from the toothed skirt.
In such drill chucks, dirt tends to accumulate in the interior and constitutes a potential and substantial danger of contamination for the chuck, especially during overhead drilling since, in this case, the detritus drops directly downwardly between the jaws into the holding fixture of the chuck and eventually causes a deterioration of the functional properties of the chuck. It thus becomes necessary to disassemble and clean the chuck, a process which is cumbersome, time consuming and usually requires the expertise of a specialist.